As a multi-room air conditioner having the plurality of indoor units, an air conditioner described in Japanese Patent Application Laid-Open No. Hei 2-133760 (Patent Literature 1) is known. In the air conditioner in this Patent Literature 1, it is described that upon cooling operation of the multi-room air conditioner, the cooling capacity of each of the plurality of indoor units is controlled using refrigerant superheat degree at the outlet of the heat exchanger in the each indoor unit.
Further, Japanese Patent No. 3956589 (Patent Literature 2) is known. In the device in this Patent Literature 2, it is presumed that as refrigerant, R32 which is HFC refrigerant with low global warming potential (GWP) is used. By using this R32, the discharge temperature of a compressor is 10 to 15° C. higher than that of R410A which is conventionally used refrigerant. To suppress rise of the discharge temperature, the vapour quality of the refrigerant at an inlet of the compressor is set to be equal to or higher than 0.65 and equal to or lower than 0.85.